A £674 million "cloud skimmer" is to begin its five year
journey through space this week to reveal what drives the violent weather on
the giant planet Jupiter and what lies beneath it's stormy clouds.

It is a planet with weather even more turbulent than the British summer.

Temperatures on Jupiter drop to -234 degrees F, thick brooding clouds obscure its atmosphere and winds blow at up to 384 miles per hour.

Now a $1.1 billion (£674 million) space probe due to launch this week is to peer through the murky clouds of the solar system's largest planet for the first time in a bid to reveal what lies beneath its stormy outer atmosphere.

On Friday the Nasa probe, named Juno after the ancient Roman goddess who spied through clouds on her husband Jupiter, is due to begin its 1,740 million mile journey to Jupiter when it is launched from Cape Canaveral in Florida.

The launch, on board an Atlas rocket, will come just over two weeks after Nasa ended its Space Shuttle programme when the last shuttle to fly, Atlantis, landed safely at the Kennedy Space Center in Florida.

Scientists hope to discover whether a mysterious material called metallic hydrogen exists inside Jupiter's atmosphere, where the pressure is so great that hydrogen gas is squeezed into a metal-like fluid that can conduct electricity.

This material is thought to be responsible for the planet's intense magnetic field and may drive the turbulent storms in the gas above.

Dr Scott Bolton, the mission's principal investigator and director of the Southwest Research Institute's Space Science Division, said: "Juno will be the first time we will be able to see down into the planet, through the clouds and see how deep the features we can see go into the planet.

"They may be just a thin outer skin or may represent something more important about Jupiter's structure and rotation."

Jupiter, the fifth planet from the Sun, is 1,321 times the size of the Earth. Violent, swirling storms and vortices thousands of miles wide sweep across its surface and are thought to be driven by wind. Lightning flashes have also been seen on the planet.

Although Jupiter is around 450 million miles from Earth, Juno will perform an elaborate loop around the Earth to build up speed with the help of our planet's gravity.

The three ton spacecraft is due to arrive at Jupiter in July 2016 where it will begin to orbit the planet for a year.

Three huge solar panel arms will help power the spacecraft in a part of the solar system that receives 25 times less sunlight than the Earth.

On board it is carrying a suite of eight instruments to help it reveal clues about how Jupiter formed and evolved.

Among the key questions that scientists hope to answer is about what sits at Jupiter's core. As a gas giant, most of the planet is made up of gas, squeezed and heated by extreme pressures.

Some astrophysicists believe, however, that Jupiter may have a solid core.

Scientists behind the mission also hope the probe will help to reveal secrets about how the solar system formed.

As a gas giant it formed early in the solar system's history while rocky planets formed later, and due to its huge size it will have lost little of the original material that made it up.

They also hope to find out what causes the powerful aurora that light up Jupiter's poles and are up to 1,000 times brighter than the aurora on Earth.

The Juno spacecraft is due to fly so close to the planet's atmosphere it will be able to directly sample the charged particles that produce the aurora.

It will also observe Jupiter's gravity and magnetic fields while measuring the composition of the atmosphere.

Dr Bolton said: "What we are trying to do is discover the recipe for planet formation. We are looking at the ingredient list and what is at the core of the planet.

"On Earth we have a permanently magnetised crust that means we can't see down very far beneath the surface of our own planet, but Jupiter doesn't have that, so we can see right the way down to the source of that magnetic field.

"All these things will help us find out what happens when planets form and what happened in the early solar system."